It has been recognized that electrical devices which are part of multiple device communication systems benefit from circuitry which enhances reliability of operation of the respective devices. In wired systems, it has been known to use end-of-line relays. The relays change state with loss of electrical energy on the lines. Such known systems, however, do not measure actual power supply voltage available for operational purposes.
In non-wired systems, it has been known to conduct local power supply tests on a periodic basis. For example, it has long been known to conduct intermittent tests of battery powered electrical devices, such as smoke detectors, to confirm that the respective battery retains sufficient energy to properly operate the respective device when needed.
Multi-device communication systems have also been known to be subject to noise problems associated with the respective communication medium. For example, electrical noise from various sources can be coupled to communication lines in wired systems. Alternately, RF interference can intermittently create noise problems in wireless systems.
Known solutions to some of these problems have included the use of filters to eliminate signals having noise related frequencies. Alternately, multiple transmissions or checksums have been used to improve the likelihood that a message has been accurately received.
While generally useful, none of the known systems have provided completely satisfactory solutions to these problems under all conditions. It would be desirable to be able to continuously monitor available energy associated with respective electric devices during normal operating conditions. It would also be desirable to be able to improve noise immunity of such devices under various operating conditions. Finally, it would be most preferable to be able to achieve these objectives without introducing extensive additional complexity or costs into the respective noises.